1. Field of the Invention
The present invention relates to a power switch assembly, arrangement or topology for a capacitive load.
2. Description of the Related Art
FIGS. 2a and 2b show a conventional power switch assembly for a capacitive load which has a common electrode on one side thereof and two discrete electrodes on an opposite side thereof. The two electrodes of capacitor C1′ represent the common electrode of the capacitive load and one of the two discrete electrodes of the capacitive load, respectively. The two electrodes of capacitor C2′ represent the common electrode of the capacitive load and the other one of the two discrete electrodes of the capacitive load, respectively. The capacitor C1′ is coupled to the voltage source V1 via four switches S1′˜S4′ and the capacitor C2′ is coupled to the voltage source V2 via four switches S5′˜S8′. Usually, the capacitive load is an ultrasonically vibrating element, such as a piezoelectric vibrator. At each time, only one of the voltage sources V1 and V2 is selected to supply power to the capacitor C1′ or C2′. When the voltage source V1 is selected to supply power to the capacitor C1′, the vibrating element can move in a first direction. When the voltage source V2 is selected to supply power to the capacitor C2′, the vibrating element can move in a second direction opposite to the first direction.
However, in the above described conventional power switch assembly, two voltage sources and eight switches are used, which results in the circuitry being complicated and costs being high.
Therefore, an improved power switch assembly for a capacitive load, which overcomes the above mentioned shortcomings, is desired.